Drafting instrument



Jan. 1, 1935. 'r. e. ALTENEDER DRAFTING INSTRUMENT Filed June 26, 1951 am I v s mamw a m we TM N 6 6 T '0 d 0 1% T A TTCRNE Y.

1 'lhis invention relates to drafting instruments.

bow-type.

Patented J an. 1, 1935 and particularly to drafting instruments of the Bow instrumentsas usually constructed- 60m prise apair 'of legs attach'ed toa handle and so arranged that ,the legs' are resiliently urged apart toward the widest setting ofthe instrument; The

f outwardurgeofthe legsis restricted and 'controlled usually by a threaded shaft lpivotally mounted in one leg and slidablymounted inthe other and provided witha rotatable threaded nut arranged to bear against the outerside of the leg through lwhich the threaded-shank: slides; Such prior art bow instruments have possessed cer- L tain disadvantages which may be summarized as; lack} of-"iirm s11pport =for the threaded shaft,

which militates 1 against freejspinning' of the threaded nutf inmaking quick adjustments of the: instrument when the legs are' manually gripped and squeezed together to relieve thenut of frie tidnaiengagem m with theleg, unduewear onthethreads of the shaft through lateralfriction due to misalignment,' and" excessive-friction" developed between the nut-andthe adjacent leg.

It is among the-"objects of this invention; to

provide a drafting instrumentwhich obviates the disadvantages of the prior constructions; toprovide a'drafting -instrument in which thethreaded shaft [joining the' l'egs of the instrument is always "held in such b'raced position asfto facilitate free spinning of "the threaded nut thereon;

to mmmea bow cornpass of such construction as to enable the use of a relatively highpitched thread 'j-for speedy" adjustments; to provide a 2 drafting] instrument havingj a pair of legs with means to secure proper andaccurate adjust- .M l g g V m t threads- 24;cutthereon-yis of ajdia'meter slightly 1 but appreciably less than the -width-ofslots"1'7 and 18+ of lgl'll and'sl'ets" 2 1- aridf22 or 1eg 12r A merits a; helegs with a minimumjfof friction re ar-Glass ,ijs bsta tia vgo ffslisht f e v lair n H alignmentro'f j'the legs; t provide a grafting in fstrumentvvith self aligning hearings; to provide ra ins i zrme har g aaa of legs with means rigidly engaging the legs for adjustment purposes. The foregoing and other objectsare attained in the purely illustrative form'of-v the invention disclosed in the accompanying drawmg. t

Referring to the drawing: r g

Fig. 1 represents a side elevation of a drafting instrument constructed according tothe invention herein,

Fig. 2 represents a fragmentary enlarged vertical section partially in full linesfithrough the adjusting mechanism and a portion of each of the spaced legs, and a l v adjustable needleltpoint 14; 1

.erably formdin Fig; 3 represents-a horizontal section. partially in full .1ines;:ofthe zra'djusting mechanism.

The instrument .is: preferably provided with a handle 10' to which legs :11 :and' 12'are connected in any-ldesired manner? Th'eqlegs ill-a and 12 are preferably Yresilie'nt tso aslto :haveuan. equal and; opposite urge awaytrrom each? other and fromi the axis -of -hand1e' 10:. arAs .is' well known .in the: art .this tma'yl the: accomplished byuhaving rigid legs actuated by; La suitabIe spring-device i (not. shown) or: by 2 providing legsi;11:andr12t 0ff'Tesilient materialbto form "the c spring bow instru-r ment disclosed in Fi'g: Althoughv thesiiends of i the instrument legs? may carry any, desired ter-L minals, foriuillustrative purposesleg 111:.carries the adjustable-dead" 13; whi1e"leg\:12:carries the L 1 Leg 11 preferably :"has an '-enlargement. 15lm,

which is atransversez horiz'ontal:cylindricalbore 16. 1Enlargemnti l5 mas a' vertical slot 517i com-J- 20; municatin'g with the bore and on the innerl'isu'r faceof the leg' i'si-provided iwith a slot 18 com-n municating with bore 16.- =;As shown in Fig. 2 the upper and lower. surface's of the respective slots: 17 and =18 are flared outwardly rmm the bore 161 to eifect clearance m the swingingl shaft to be describedr Leg 12 is 'similarly provided with' a;

horizontal" cylindrical ore: 201 and an i outwardly directed and upwardly} and outwardly *flared' verticaltslot 21 communicating'with the bo re2O, and with aminwardly directed;flared vertical slot 22 'also communicating with the 'bore 20;- As willbe: notedthese slots 2l and 22 and bore 20@ are pref e 1214mm enlargement 19- thereof.

5" A l Sh'af cylindrical barrel '25" having s'lidable and-f'rov v y "f leg ll has ia transverse bere ae of a "diameter to receive '-the fixed end of shaft 23 after it is disposed in registry therewith through slot 18 of the leg 11. The shaft 23 isanchored in the barrel 25 in: any suitable manner as by the axial pin 27 disposed in a suitablebore of barrel 25 and passing through a registering bore in the end of shaft 23. It will be observed, and it is a feature of importance, that barrel 25 and shaft 23 as a unit may have a horizontal movement relative to the leg 11 limited is free to rotatejin' thebore ZO and also to have axial horizontal" sliding movementtherein;

An adjusting nut 32, preferably provided with a milled peripheral edge 33, may be threaded.-

upon the threads 24 of shaft 23 and ispreferably provided with a reduced axial prolongation" or 1 hub 34 having the curved edge ,35 .ofgsuchcurva ture as to sink within the counter-sink and, en: gage upon the counter-sunlr'surfacefil" of the bore 30 of the bearing 28. In this connection it might be observed that the counter-sink 31 is elliptical in contour owingto its formation in the side of .theieylinder butl-is adequate to'form a rig id engagement :of the adjusting nutwith the slidable bearing28.f It will be'obser'ved thatithe lat eral fiareof the slot-i21 lega12 is such as to provide adequate clearancesfor'the hub 34 tofallowlateral movement of thetshaftibearing 28 and adjusting nut 32 asa'unitu ItTwill also be ob-.-

served that N such 1' permissible lateral movement has no adverse'efiect on the'setting of the legs.

-.To:-secure quick'adjustmentszthe operator may manually engage: and squeeze: the legstoward each .other with .thsimmediate-.:eifect"of withdrawing; the adjustingscrew hub. 34 from its en gagement with the countersink 31 of the barrel.

28. Whereas in'-1ordinary prior constructions the shaft 23 has thereafter. beenz' free, to swing up ytateg minor ,misalign mentsof the slots :15]; and;

and down vertically in anielon'gatedslotin leg 12 which has resultedinisuch absence ofufi'rm support .for the shaft as to militate against'free spinning .of the adjusting 1 nut 32, it.- wil'I-"bel observed that the shaft 23 :is" guided. and firmly;

supportedlby .its engagement in the bearing :28

' so that free spinning of thewadjusting screw is facilitated. Whereas in prior art constructions the anchored end of shaft 23;has1been incapable of horizontal adjustment-and it has sometimes occurred that theshaft .23", ,swingable a fixed vertical plane has been out of registry with :theappropriate ,slots in the tcooperating leg so as to cause-a lateral 'bindingactionj on the, shaft, ,ac-

companied by distortion when the adjusting nut was-tightened, ityis to be observed. that owing tothe facility with which. eithenpr both the cyline 1drical barrel 25 and the cylindrical bearing 28,

may move axially; of the bores in zwhichith y r0.-

180ff leg '11 relative tqthe slots- 21; and" 22 of leg 12 are 'jimmediatelyi compensatedwfor by selfalignment of either; or; both of the rotatable elementsin- ,their{xrespeetive bores. ;It-,be ob ,servedalsothat asqtliethreaded adjusting nut,

32 has a certain definite coaxial relation to shaft 23 and as the diametric bore 30 of the adjustable bearing 28 has a guiding sliding engagement with shaft 23, the bearing 28 is always properly disposed, regardless of the closeness or remoteness of the legs, as to cause proper guiding interengagement of the curved end 35 of hub 34 in the counter-sink 31.

As noted the invention is susceptible to various changes and modifications all of which are to be construed as within the scope of the inven-' tion unless otherwise limited in the appended claims.

.I claim:

li'In aninstrument, a pair of legs, each leg having a'transverse'bore and slots communicatingtherewith, av shaft of smaller diameter than the width of said slots, means for pivoting the shaft inthe bore of one leg while permitting lateral movement of said pivot, and meansfor guidinglthe shaft in the boreof the, other leg while permitting lateral movement of the shaft in thebore.

- 2. In a drafting'instrument, a pair of legs, a

threaded shaft, one of said legs, having a guid-- ing slotv to slidably receive the threaded shaft,-

means for pivotally mounting theshaft on the other leg, said'means being arranged for transverse sliding movement relative; to said lastmentioned other leg to permit registration of said shaft with the guiding slot in thefirst mentioned leg; Y

"3. In a drafting instrument, a pair of legs, a

threaded shaft, one-of. said legs having a guiding slot to slidably receive the threaded shaft, a slot beinggformed in the other leg of greater width:

than the diameter of said shaft, said other leg having a transverse bore communicating with the slot, a barrel slidably androtatably mounted in said bore, said shaft connected to saidbarrel and arranged to pivot therewith in the bore, and

said barrelbeing arranged for, axial movement to insure'registration.ofsaid shaft-with the slot in the firstmentioned leg.-

4. In an instrument, a pairj of legs, one leg having'a transverse cylindrical-bore and having a slot communicating with the-bore, acylindrical barrel slidably and rotatably mounted in the transverse bore and-having-a diametrical' bore of smaller diameter than the widthof the'slot and terminating in a countersink, a threaded shaft pivotally mounted on the other ofsaid legs and extending through 'the diametric bore and .countersink and theslot inv the first mentionedleg; a nut having an axial tapering extension and threaded on said shaft, the extension and slotin said leg being so arranged that the extension enters the countersink and frictionally holds the shaft'and the cylindrical barreltogether withe outbinding on an edge of the slot inthe leg.

THEODORE ALTEN'EDER, 

